多线程的死锁

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原因： 同时争夺同一资源导致死锁， 两个线程，彼此在等待对方占据的锁

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Thread1

public class Thread1 extends Thread {
    Object o1;
    Object o2;

    public Thread1(Object o1, Object o2) {
        this.o1 = o1;
        this.o2 = o2;
    }

    @Override
    public void run() {
        synchronized (o1){
            System.out.println("进入线程 1 锁定对象 1");
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (o2){
                System.out.println("进入线程 1 锁定对象 2");
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("进入线程 1 释放对象 2");
            }
            System.out.println("进入线程 1 释放对象 1");
        }
    }
}

Thread2

public class Thread2 extends Thread {
    Object o1;
    Object o2;

    public Thread2(Object o1, Object o2) {
        this.o1 = o1;
        this.o2 = o2;
    }

    @Override
    public void run() {
        synchronized (o2){
            System.out.println("进入线程 2 锁定对象 2");
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (o1){
                System.out.println("进入线程 2 锁定对象 1");
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("进入线程 2 释放对象 1");
            }
            System.out.println("进入线程 2 释放对象 2");
        }
    }
}

测试

public class Main {
    public static void main(String[] args) {
        Object o1 = new Object();
        Object o2 = new Object();
        Thread1 thread1 = new Thread1(o1, o2);
        Thread2 thread2 = new Thread2(o1, o2);

        thread1.start();
        thread2.start();
    }
}

结果

result.gif